xref: /linux/drivers/net/ethernet/realtek/atp.c (revision 87c9c16317882dd6dbbc07e349bc3223e14f3244)
1 /* atp.c: Attached (pocket) ethernet adapter driver for linux. */
2 /*
3 	This is a driver for commonly OEM pocket (parallel port)
4 	ethernet adapters based on the Realtek RTL8002 and RTL8012 chips.
5 
6 	Written 1993-2000 by Donald Becker.
7 
8 	This software may be used and distributed according to the terms of
9 	the GNU General Public License (GPL), incorporated herein by reference.
10 	Drivers based on or derived from this code fall under the GPL and must
11 	retain the authorship, copyright and license notice.  This file is not
12 	a complete program and may only be used when the entire operating
13 	system is licensed under the GPL.
14 
15 	Copyright 1993 United States Government as represented by the Director,
16 	National Security Agency.  Copyright 1994-2000 retained by the original
17 	author, Donald Becker. The timer-based reset code was supplied in 1995
18 	by Bill Carlson, wwc@super.org.
19 
20 	The author may be reached as becker@scyld.com, or C/O
21 	Scyld Computing Corporation
22 	410 Severn Ave., Suite 210
23 	Annapolis MD 21403
24 
25 	Support information and updates available at
26 	http://www.scyld.com/network/atp.html
27 
28 
29 	Modular support/softnet added by Alan Cox.
30 	_bit abuse fixed up by Alan Cox
31 
32 */
33 
34 static const char version[] =
35 "atp.c:v1.09=ac 2002/10/01 Donald Becker <becker@scyld.com>\n";
36 
37 /* The user-configurable values.
38    These may be modified when a driver module is loaded.*/
39 
40 static int debug = 1; 			/* 1 normal messages, 0 quiet .. 7 verbose. */
41 #define net_debug debug
42 
43 /* Maximum events (Rx packets, etc.) to handle at each interrupt. */
44 static int max_interrupt_work = 15;
45 
46 #define NUM_UNITS 2
47 /* The standard set of ISA module parameters. */
48 static int io[NUM_UNITS];
49 static int irq[NUM_UNITS];
50 static int xcvr[NUM_UNITS]; 			/* The data transfer mode. */
51 
52 /* Operational parameters that are set at compile time. */
53 
54 /* Time in jiffies before concluding the transmitter is hung. */
55 #define TX_TIMEOUT  (400*HZ/1000)
56 
57 /*
58 	This file is a device driver for the RealTek (aka AT-Lan-Tec) pocket
59 	ethernet adapter.  This is a common low-cost OEM pocket ethernet
60 	adapter, sold under many names.
61 
62   Sources:
63 	This driver was written from the packet driver assembly code provided by
64 	Vincent Bono of AT-Lan-Tec.	 Ever try to figure out how a complicated
65 	device works just from the assembly code?  It ain't pretty.  The following
66 	description is written based on guesses and writing lots of special-purpose
67 	code to test my theorized operation.
68 
69 	In 1997 Realtek made available the documentation for the second generation
70 	RTL8012 chip, which has lead to several driver improvements.
71 	  http://www.realtek.com.tw/
72 
73 					Theory of Operation
74 
75 	The RTL8002 adapter seems to be built around a custom spin of the SEEQ
76 	controller core.  It probably has a 16K or 64K internal packet buffer, of
77 	which the first 4K is devoted to transmit and the rest to receive.
78 	The controller maintains the queue of received packet and the packet buffer
79 	access pointer internally, with only 'reset to beginning' and 'skip to next
80 	packet' commands visible.  The transmit packet queue holds two (or more?)
81 	packets: both 'retransmit this packet' (due to collision) and 'transmit next
82 	packet' commands must be started by hand.
83 
84 	The station address is stored in a standard bit-serial EEPROM which must be
85 	read (ughh) by the device driver.  (Provisions have been made for
86 	substituting a 74S288 PROM, but I haven't gotten reports of any models
87 	using it.)  Unlike built-in devices, a pocket adapter can temporarily lose
88 	power without indication to the device driver.  The major effect is that
89 	the station address, receive filter (promiscuous, etc.) and transceiver
90 	must be reset.
91 
92 	The controller itself has 16 registers, some of which use only the lower
93 	bits.  The registers are read and written 4 bits at a time.  The four bit
94 	register address is presented on the data lines along with a few additional
95 	timing and control bits.  The data is then read from status port or written
96 	to the data port.
97 
98 	Correction: the controller has two banks of 16 registers.  The second
99 	bank contains only the multicast filter table (now used) and the EEPROM
100 	access registers.
101 
102 	Since the bulk data transfer of the actual packets through the slow
103 	parallel port dominates the driver's running time, four distinct data
104 	(non-register) transfer modes are provided by the adapter, two in each
105 	direction.  In the first mode timing for the nibble transfers is
106 	provided through the data port.  In the second mode the same timing is
107 	provided through the control port.  In either case the data is read from
108 	the status port and written to the data port, just as it is accessing
109 	registers.
110 
111 	In addition to the basic data transfer methods, several more are modes are
112 	created by adding some delay by doing multiple reads of the data to allow
113 	it to stabilize.  This delay seems to be needed on most machines.
114 
115 	The data transfer mode is stored in the 'dev->if_port' field.  Its default
116 	value is '4'.  It may be overridden at boot-time using the third parameter
117 	to the "ether=..." initialization.
118 
119 	The header file <atp.h> provides inline functions that encapsulate the
120 	register and data access methods.  These functions are hand-tuned to
121 	generate reasonable object code.  This header file also documents my
122 	interpretations of the device registers.
123 */
124 
125 #include <linux/kernel.h>
126 #include <linux/module.h>
127 #include <linux/types.h>
128 #include <linux/fcntl.h>
129 #include <linux/interrupt.h>
130 #include <linux/ioport.h>
131 #include <linux/in.h>
132 #include <linux/string.h>
133 #include <linux/errno.h>
134 #include <linux/init.h>
135 #include <linux/crc32.h>
136 #include <linux/netdevice.h>
137 #include <linux/etherdevice.h>
138 #include <linux/skbuff.h>
139 #include <linux/spinlock.h>
140 #include <linux/delay.h>
141 #include <linux/bitops.h>
142 
143 #include <asm/io.h>
144 #include <asm/dma.h>
145 
146 #include "atp.h"
147 
148 MODULE_AUTHOR("Donald Becker <becker@scyld.com>");
149 MODULE_DESCRIPTION("RealTek RTL8002/8012 parallel port Ethernet driver");
150 MODULE_LICENSE("GPL");
151 
152 module_param(max_interrupt_work, int, 0);
153 module_param(debug, int, 0);
154 module_param_hw_array(io, int, ioport, NULL, 0);
155 module_param_hw_array(irq, int, irq, NULL, 0);
156 module_param_array(xcvr, int, NULL, 0);
157 MODULE_PARM_DESC(max_interrupt_work, "ATP maximum events handled per interrupt");
158 MODULE_PARM_DESC(debug, "ATP debug level (0-7)");
159 MODULE_PARM_DESC(io, "ATP I/O base address(es)");
160 MODULE_PARM_DESC(irq, "ATP IRQ number(s)");
161 MODULE_PARM_DESC(xcvr, "ATP transceiver(s) (0=internal, 1=external)");
162 
163 /* The number of low I/O ports used by the ethercard. */
164 #define ETHERCARD_TOTAL_SIZE	3
165 
166 /* Sequence to switch an 8012 from printer mux to ethernet mode. */
167 static char mux_8012[] = { 0xff, 0xf7, 0xff, 0xfb, 0xf3, 0xfb, 0xff, 0xf7,};
168 
169 struct net_local {
170     spinlock_t lock;
171     struct net_device *next_module;
172     struct timer_list timer;	/* Media selection timer. */
173     struct net_device *dev;	/* Timer dev. */
174     unsigned long last_rx_time;	/* Last Rx, in jiffies, to handle Rx hang. */
175     int saved_tx_size;
176     unsigned int tx_unit_busy:1;
177     unsigned char re_tx,	/* Number of packet retransmissions. */
178 		addr_mode,		/* Current Rx filter e.g. promiscuous, etc. */
179 		pac_cnt_in_tx_buf;
180 };
181 
182 /* This code, written by wwc@super.org, resets the adapter every
183    TIMED_CHECKER ticks.  This recovers from an unknown error which
184    hangs the device. */
185 #define TIMED_CHECKER (HZ/4)
186 #ifdef TIMED_CHECKER
187 #include <linux/timer.h>
188 static void atp_timed_checker(struct timer_list *t);
189 #endif
190 
191 /* Index to functions, as function prototypes. */
192 
193 static int atp_probe1(long ioaddr);
194 static void get_node_ID(struct net_device *dev);
195 static unsigned short eeprom_op(long ioaddr, unsigned int cmd);
196 static int net_open(struct net_device *dev);
197 static void hardware_init(struct net_device *dev);
198 static void write_packet(long ioaddr, int length, unsigned char *packet, int pad, int mode);
199 static void trigger_send(long ioaddr, int length);
200 static netdev_tx_t atp_send_packet(struct sk_buff *skb,
201 				   struct net_device *dev);
202 static irqreturn_t atp_interrupt(int irq, void *dev_id);
203 static void net_rx(struct net_device *dev);
204 static void read_block(long ioaddr, int length, unsigned char *buffer, int data_mode);
205 static int net_close(struct net_device *dev);
206 static void set_rx_mode(struct net_device *dev);
207 static void tx_timeout(struct net_device *dev, unsigned int txqueue);
208 
209 
210 /* A list of all installed ATP devices, for removing the driver module. */
211 static struct net_device *root_atp_dev;
212 
213 /* Check for a network adapter of this type, and return '0' iff one exists.
214    If dev->base_addr == 0, probe all likely locations.
215    If dev->base_addr == 1, always return failure.
216    If dev->base_addr == 2, allocate space for the device and return success
217    (detachable devices only).
218 
219    FIXME: we should use the parport layer for this
220    */
221 static int __init atp_init(void)
222 {
223 	int *port, ports[] = {0x378, 0x278, 0x3bc, 0};
224 	int base_addr = io[0];
225 
226 	if (base_addr > 0x1ff)		/* Check a single specified location. */
227 		return atp_probe1(base_addr);
228 	else if (base_addr == 1)	/* Don't probe at all. */
229 		return -ENXIO;
230 
231 	for (port = ports; *port; port++) {
232 		long ioaddr = *port;
233 		outb(0x57, ioaddr + PAR_DATA);
234 		if (inb(ioaddr + PAR_DATA) != 0x57)
235 			continue;
236 		if (atp_probe1(ioaddr) == 0)
237 			return 0;
238 	}
239 
240 	return -ENODEV;
241 }
242 
243 static const struct net_device_ops atp_netdev_ops = {
244 	.ndo_open		= net_open,
245 	.ndo_stop		= net_close,
246 	.ndo_start_xmit		= atp_send_packet,
247 	.ndo_set_rx_mode	= set_rx_mode,
248 	.ndo_tx_timeout		= tx_timeout,
249 	.ndo_set_mac_address 	= eth_mac_addr,
250 	.ndo_validate_addr	= eth_validate_addr,
251 };
252 
253 static int __init atp_probe1(long ioaddr)
254 {
255 	struct net_device *dev = NULL;
256 	struct net_local *lp;
257 	int saved_ctrl_reg, status, i;
258 	int res;
259 
260 	outb(0xff, ioaddr + PAR_DATA);
261 	/* Save the original value of the Control register, in case we guessed
262 	   wrong. */
263 	saved_ctrl_reg = inb(ioaddr + PAR_CONTROL);
264 	if (net_debug > 3)
265 		printk("atp: Control register was %#2.2x.\n", saved_ctrl_reg);
266 	/* IRQEN=0, SLCTB=high INITB=high, AUTOFDB=high, STBB=high. */
267 	outb(0x04, ioaddr + PAR_CONTROL);
268 #ifndef final_version
269 	if (net_debug > 3) {
270 		/* Turn off the printer multiplexer on the 8012. */
271 		for (i = 0; i < 8; i++)
272 			outb(mux_8012[i], ioaddr + PAR_DATA);
273 		write_reg(ioaddr, MODSEL, 0x00);
274 		printk("atp: Registers are ");
275 		for (i = 0; i < 32; i++)
276 			printk(" %2.2x", read_nibble(ioaddr, i));
277 		printk(".\n");
278 	}
279 #endif
280 	/* Turn off the printer multiplexer on the 8012. */
281 	for (i = 0; i < 8; i++)
282 		outb(mux_8012[i], ioaddr + PAR_DATA);
283 	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
284 	/* udelay() here? */
285 	status = read_nibble(ioaddr, CMR1);
286 
287 	if (net_debug > 3) {
288 		printk(KERN_DEBUG "atp: Status nibble was %#2.2x..", status);
289 		for (i = 0; i < 32; i++)
290 			printk(" %2.2x", read_nibble(ioaddr, i));
291 		printk("\n");
292 	}
293 
294 	if ((status & 0x78) != 0x08) {
295 		/* The pocket adapter probe failed, restore the control register. */
296 		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
297 		return -ENODEV;
298 	}
299 	status = read_nibble(ioaddr, CMR2_h);
300 	if ((status & 0x78) != 0x10) {
301 		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
302 		return -ENODEV;
303 	}
304 
305 	dev = alloc_etherdev(sizeof(struct net_local));
306 	if (!dev)
307 		return -ENOMEM;
308 
309 	/* Find the IRQ used by triggering an interrupt. */
310 	write_reg_byte(ioaddr, CMR2, 0x01);			/* No accept mode, IRQ out. */
311 	write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);	/* Enable Tx and Rx. */
312 
313 	/* Omit autoIRQ routine for now. Use "table lookup" instead.  Uhgggh. */
314 	if (irq[0])
315 		dev->irq = irq[0];
316 	else if (ioaddr == 0x378)
317 		dev->irq = 7;
318 	else
319 		dev->irq = 5;
320 	write_reg_high(ioaddr, CMR1, CMR1h_TxRxOFF); /* Disable Tx and Rx units. */
321 	write_reg(ioaddr, CMR2, CMR2_NULL);
322 
323 	dev->base_addr = ioaddr;
324 
325 	/* Read the station address PROM.  */
326 	get_node_ID(dev);
327 
328 #ifndef MODULE
329 	if (net_debug)
330 		printk(KERN_INFO "%s", version);
331 #endif
332 
333 	printk(KERN_NOTICE "%s: Pocket adapter found at %#3lx, IRQ %d, "
334 	       "SAPROM %pM.\n",
335 	       dev->name, dev->base_addr, dev->irq, dev->dev_addr);
336 
337 	/* Reset the ethernet hardware and activate the printer pass-through. */
338 	write_reg_high(ioaddr, CMR1, CMR1h_RESET | CMR1h_MUX);
339 
340 	lp = netdev_priv(dev);
341 	lp->addr_mode = CMR2h_Normal;
342 	spin_lock_init(&lp->lock);
343 
344 	/* For the ATP adapter the "if_port" is really the data transfer mode. */
345 	if (xcvr[0])
346 		dev->if_port = xcvr[0];
347 	else
348 		dev->if_port = (dev->mem_start & 0xf) ? (dev->mem_start & 0x7) : 4;
349 	if (dev->mem_end & 0xf)
350 		net_debug = dev->mem_end & 7;
351 
352 	dev->netdev_ops 	= &atp_netdev_ops;
353 	dev->watchdog_timeo	= TX_TIMEOUT;
354 
355 	res = register_netdev(dev);
356 	if (res) {
357 		free_netdev(dev);
358 		return res;
359 	}
360 
361 	lp->next_module = root_atp_dev;
362 	root_atp_dev = dev;
363 
364 	return 0;
365 }
366 
367 /* Read the station address PROM, usually a word-wide EEPROM. */
368 static void __init get_node_ID(struct net_device *dev)
369 {
370 	long ioaddr = dev->base_addr;
371 	int sa_offset = 0;
372 	int i;
373 
374 	write_reg(ioaddr, CMR2, CMR2_EEPROM);	  /* Point to the EEPROM control registers. */
375 
376 	/* Some adapters have the station address at offset 15 instead of offset
377 	   zero.  Check for it, and fix it if needed. */
378 	if (eeprom_op(ioaddr, EE_READ(0)) == 0xffff)
379 		sa_offset = 15;
380 
381 	for (i = 0; i < 3; i++)
382 		((__be16 *)dev->dev_addr)[i] =
383 			cpu_to_be16(eeprom_op(ioaddr, EE_READ(sa_offset + i)));
384 
385 	write_reg(ioaddr, CMR2, CMR2_NULL);
386 }
387 
388 /*
389   An EEPROM read command starts by shifting out 0x60+address, and then
390   shifting in the serial data. See the NatSemi databook for details.
391  *		   ________________
392  * CS : __|
393  *			   ___	   ___
394  * CLK: ______|	  |___|	  |
395  *		 __ _______ _______
396  * DI :	 __X_______X_______X
397  * DO :	 _________X_______X
398  */
399 
400 static unsigned short __init eeprom_op(long ioaddr, u32 cmd)
401 {
402 	unsigned eedata_out = 0;
403 	int num_bits = EE_CMD_SIZE;
404 
405 	while (--num_bits >= 0) {
406 		char outval = (cmd & (1<<num_bits)) ? EE_DATA_WRITE : 0;
407 		write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_LOW);
408 		write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_HIGH);
409 		eedata_out <<= 1;
410 		if (read_nibble(ioaddr, PROM_DATA) & EE_DATA_READ)
411 			eedata_out++;
412 	}
413 	write_reg_high(ioaddr, PROM_CMD, EE_CLK_LOW & ~EE_CS);
414 	return eedata_out;
415 }
416 
417 
418 /* Open/initialize the board.  This is called (in the current kernel)
419    sometime after booting when the 'ifconfig' program is run.
420 
421    This routine sets everything up anew at each open, even
422    registers that "should" only need to be set once at boot, so that
423    there is non-reboot way to recover if something goes wrong.
424 
425    This is an attachable device: if there is no private entry then it wasn't
426    probed for at boot-time, and we need to probe for it again.
427    */
428 static int net_open(struct net_device *dev)
429 {
430 	struct net_local *lp = netdev_priv(dev);
431 	int ret;
432 
433 	/* The interrupt line is turned off (tri-stated) when the device isn't in
434 	   use.  That's especially important for "attached" interfaces where the
435 	   port or interrupt may be shared. */
436 	ret = request_irq(dev->irq, atp_interrupt, 0, dev->name, dev);
437 	if (ret)
438 		return ret;
439 
440 	hardware_init(dev);
441 
442 	lp->dev = dev;
443 	timer_setup(&lp->timer, atp_timed_checker, 0);
444 	lp->timer.expires = jiffies + TIMED_CHECKER;
445 	add_timer(&lp->timer);
446 
447 	netif_start_queue(dev);
448 	return 0;
449 }
450 
451 /* This routine resets the hardware.  We initialize everything, assuming that
452    the hardware may have been temporarily detached. */
453 static void hardware_init(struct net_device *dev)
454 {
455 	struct net_local *lp = netdev_priv(dev);
456 	long ioaddr = dev->base_addr;
457 	int i;
458 
459 	/* Turn off the printer multiplexer on the 8012. */
460 	for (i = 0; i < 8; i++)
461 		outb(mux_8012[i], ioaddr + PAR_DATA);
462 	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
463 
464 	for (i = 0; i < 6; i++)
465 		write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);
466 
467 	write_reg_high(ioaddr, CMR2, lp->addr_mode);
468 
469 	if (net_debug > 2) {
470 		printk(KERN_DEBUG "%s: Reset: current Rx mode %d.\n", dev->name,
471 			   (read_nibble(ioaddr, CMR2_h) >> 3) & 0x0f);
472 	}
473 
474 	write_reg(ioaddr, CMR2, CMR2_IRQOUT);
475 	write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);
476 
477 	/* Enable the interrupt line from the serial port. */
478 	outb(Ctrl_SelData + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
479 
480 	/* Unmask the interesting interrupts. */
481 	write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);
482 	write_reg_high(ioaddr, IMR, ISRh_RxErr);
483 
484 	lp->tx_unit_busy = 0;
485 	lp->pac_cnt_in_tx_buf = 0;
486 	lp->saved_tx_size = 0;
487 }
488 
489 static void trigger_send(long ioaddr, int length)
490 {
491 	write_reg_byte(ioaddr, TxCNT0, length & 0xff);
492 	write_reg(ioaddr, TxCNT1, length >> 8);
493 	write_reg(ioaddr, CMR1, CMR1_Xmit);
494 }
495 
496 static void write_packet(long ioaddr, int length, unsigned char *packet, int pad_len, int data_mode)
497 {
498     if (length & 1)
499     {
500     	length++;
501     	pad_len++;
502     }
503 
504     outb(EOC+MAR, ioaddr + PAR_DATA);
505     if ((data_mode & 1) == 0) {
506 		/* Write the packet out, starting with the write addr. */
507 		outb(WrAddr+MAR, ioaddr + PAR_DATA);
508 		do {
509 			write_byte_mode0(ioaddr, *packet++);
510 		} while (--length > pad_len) ;
511 		do {
512 			write_byte_mode0(ioaddr, 0);
513 		} while (--length > 0) ;
514     } else {
515 		/* Write the packet out in slow mode. */
516 		unsigned char outbyte = *packet++;
517 
518 		outb(Ctrl_LNibWrite + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
519 		outb(WrAddr+MAR, ioaddr + PAR_DATA);
520 
521 		outb((outbyte & 0x0f)|0x40, ioaddr + PAR_DATA);
522 		outb(outbyte & 0x0f, ioaddr + PAR_DATA);
523 		outbyte >>= 4;
524 		outb(outbyte & 0x0f, ioaddr + PAR_DATA);
525 		outb(Ctrl_HNibWrite + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
526 		while (--length > pad_len)
527 			write_byte_mode1(ioaddr, *packet++);
528 		while (--length > 0)
529 			write_byte_mode1(ioaddr, 0);
530     }
531     /* Terminate the Tx frame.  End of write: ECB. */
532     outb(0xff, ioaddr + PAR_DATA);
533     outb(Ctrl_HNibWrite | Ctrl_SelData | Ctrl_IRQEN, ioaddr + PAR_CONTROL);
534 }
535 
536 static void tx_timeout(struct net_device *dev, unsigned int txqueue)
537 {
538 	long ioaddr = dev->base_addr;
539 
540 	printk(KERN_WARNING "%s: Transmit timed out, %s?\n", dev->name,
541 		   inb(ioaddr + PAR_CONTROL) & 0x10 ? "network cable problem"
542 		   :  "IRQ conflict");
543 	dev->stats.tx_errors++;
544 	/* Try to restart the adapter. */
545 	hardware_init(dev);
546 	netif_trans_update(dev); /* prevent tx timeout */
547 	netif_wake_queue(dev);
548 	dev->stats.tx_errors++;
549 }
550 
551 static netdev_tx_t atp_send_packet(struct sk_buff *skb,
552 				   struct net_device *dev)
553 {
554 	struct net_local *lp = netdev_priv(dev);
555 	long ioaddr = dev->base_addr;
556 	int length;
557 	unsigned long flags;
558 
559 	length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;
560 
561 	netif_stop_queue(dev);
562 
563 	/* Disable interrupts by writing 0x00 to the Interrupt Mask Register.
564 	   This sequence must not be interrupted by an incoming packet. */
565 
566 	spin_lock_irqsave(&lp->lock, flags);
567 	write_reg(ioaddr, IMR, 0);
568 	write_reg_high(ioaddr, IMR, 0);
569 	spin_unlock_irqrestore(&lp->lock, flags);
570 
571 	write_packet(ioaddr, length, skb->data, length-skb->len, dev->if_port);
572 
573 	lp->pac_cnt_in_tx_buf++;
574 	if (lp->tx_unit_busy == 0) {
575 		trigger_send(ioaddr, length);
576 		lp->saved_tx_size = 0; 				/* Redundant */
577 		lp->re_tx = 0;
578 		lp->tx_unit_busy = 1;
579 	} else
580 		lp->saved_tx_size = length;
581 	/* Re-enable the LPT interrupts. */
582 	write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);
583 	write_reg_high(ioaddr, IMR, ISRh_RxErr);
584 
585 	dev_kfree_skb (skb);
586 	return NETDEV_TX_OK;
587 }
588 
589 
590 /* The typical workload of the driver:
591    Handle the network interface interrupts. */
592 static irqreturn_t atp_interrupt(int irq, void *dev_instance)
593 {
594 	struct net_device *dev = dev_instance;
595 	struct net_local *lp;
596 	long ioaddr;
597 	static int num_tx_since_rx;
598 	int boguscount = max_interrupt_work;
599 	int handled = 0;
600 
601 	ioaddr = dev->base_addr;
602 	lp = netdev_priv(dev);
603 
604 	spin_lock(&lp->lock);
605 
606 	/* Disable additional spurious interrupts. */
607 	outb(Ctrl_SelData, ioaddr + PAR_CONTROL);
608 
609 	/* The adapter's output is currently the IRQ line, switch it to data. */
610 	write_reg(ioaddr, CMR2, CMR2_NULL);
611 	write_reg(ioaddr, IMR, 0);
612 
613 	if (net_debug > 5)
614 		printk(KERN_DEBUG "%s: In interrupt ", dev->name);
615 	while (--boguscount > 0) {
616 		int status = read_nibble(ioaddr, ISR);
617 		if (net_debug > 5)
618 			printk("loop status %02x..", status);
619 
620 		if (status & (ISR_RxOK<<3)) {
621 			handled = 1;
622 			write_reg(ioaddr, ISR, ISR_RxOK); /* Clear the Rx interrupt. */
623 			do {
624 				int read_status = read_nibble(ioaddr, CMR1);
625 				if (net_debug > 6)
626 					printk("handling Rx packet %02x..", read_status);
627 				/* We acknowledged the normal Rx interrupt, so if the interrupt
628 				   is still outstanding we must have a Rx error. */
629 				if (read_status & (CMR1_IRQ << 3)) { /* Overrun. */
630 					dev->stats.rx_over_errors++;
631 					/* Set to no-accept mode long enough to remove a packet. */
632 					write_reg_high(ioaddr, CMR2, CMR2h_OFF);
633 					net_rx(dev);
634 					/* Clear the interrupt and return to normal Rx mode. */
635 					write_reg_high(ioaddr, ISR, ISRh_RxErr);
636 					write_reg_high(ioaddr, CMR2, lp->addr_mode);
637 				} else if ((read_status & (CMR1_BufEnb << 3)) == 0) {
638 					net_rx(dev);
639 					num_tx_since_rx = 0;
640 				} else
641 					break;
642 			} while (--boguscount > 0);
643 		} else if (status & ((ISR_TxErr + ISR_TxOK)<<3)) {
644 			handled = 1;
645 			if (net_debug > 6)
646 				printk("handling Tx done..");
647 			/* Clear the Tx interrupt.  We should check for too many failures
648 			   and reinitialize the adapter. */
649 			write_reg(ioaddr, ISR, ISR_TxErr + ISR_TxOK);
650 			if (status & (ISR_TxErr<<3)) {
651 				dev->stats.collisions++;
652 				if (++lp->re_tx > 15) {
653 					dev->stats.tx_aborted_errors++;
654 					hardware_init(dev);
655 					break;
656 				}
657 				/* Attempt to retransmit. */
658 				if (net_debug > 6)  printk("attempting to ReTx");
659 				write_reg(ioaddr, CMR1, CMR1_ReXmit + CMR1_Xmit);
660 			} else {
661 				/* Finish up the transmit. */
662 				dev->stats.tx_packets++;
663 				lp->pac_cnt_in_tx_buf--;
664 				if ( lp->saved_tx_size) {
665 					trigger_send(ioaddr, lp->saved_tx_size);
666 					lp->saved_tx_size = 0;
667 					lp->re_tx = 0;
668 				} else
669 					lp->tx_unit_busy = 0;
670 				netif_wake_queue(dev);	/* Inform upper layers. */
671 			}
672 			num_tx_since_rx++;
673 		} else if (num_tx_since_rx > 8 &&
674 			   time_after(jiffies, lp->last_rx_time + HZ)) {
675 			if (net_debug > 2)
676 				printk(KERN_DEBUG "%s: Missed packet? No Rx after %d Tx and "
677 					   "%ld jiffies status %02x  CMR1 %02x.\n", dev->name,
678 					   num_tx_since_rx, jiffies - lp->last_rx_time, status,
679 					   (read_nibble(ioaddr, CMR1) >> 3) & 15);
680 			dev->stats.rx_missed_errors++;
681 			hardware_init(dev);
682 			num_tx_since_rx = 0;
683 			break;
684 		} else
685 			break;
686 	}
687 
688 	/* This following code fixes a rare (and very difficult to track down)
689 	   problem where the adapter forgets its ethernet address. */
690 	{
691 		int i;
692 		for (i = 0; i < 6; i++)
693 			write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);
694 #if 0 && defined(TIMED_CHECKER)
695 		mod_timer(&lp->timer, jiffies + TIMED_CHECKER);
696 #endif
697 	}
698 
699 	/* Tell the adapter that it can go back to using the output line as IRQ. */
700 	write_reg(ioaddr, CMR2, CMR2_IRQOUT);
701 	/* Enable the physical interrupt line, which is sure to be low until.. */
702 	outb(Ctrl_SelData + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
703 	/* .. we enable the interrupt sources. */
704 	write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);
705 	write_reg_high(ioaddr, IMR, ISRh_RxErr); 			/* Hmmm, really needed? */
706 
707 	spin_unlock(&lp->lock);
708 
709 	if (net_debug > 5) printk("exiting interrupt.\n");
710 	return IRQ_RETVAL(handled);
711 }
712 
713 #ifdef TIMED_CHECKER
714 /* This following code fixes a rare (and very difficult to track down)
715    problem where the adapter forgets its ethernet address. */
716 static void atp_timed_checker(struct timer_list *t)
717 {
718 	struct net_local *lp = from_timer(lp, t, timer);
719 	struct net_device *dev = lp->dev;
720 	long ioaddr = dev->base_addr;
721 	int tickssofar = jiffies - lp->last_rx_time;
722 	int i;
723 
724 	spin_lock(&lp->lock);
725 	if (tickssofar > 2*HZ) {
726 #if 1
727 		for (i = 0; i < 6; i++)
728 			write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);
729 		lp->last_rx_time = jiffies;
730 #else
731 		for (i = 0; i < 6; i++)
732 			if (read_cmd_byte(ioaddr, PAR0 + i) != atp_timed_dev->dev_addr[i])
733 				{
734 			struct net_local *lp = netdev_priv(atp_timed_dev);
735 			write_reg_byte(ioaddr, PAR0 + i, atp_timed_dev->dev_addr[i]);
736 			if (i == 2)
737 			  dev->stats.tx_errors++;
738 			else if (i == 3)
739 			  dev->stats.tx_dropped++;
740 			else if (i == 4)
741 			  dev->stats.collisions++;
742 			else
743 			  dev->stats.rx_errors++;
744 		  }
745 #endif
746 	}
747 	spin_unlock(&lp->lock);
748 	lp->timer.expires = jiffies + TIMED_CHECKER;
749 	add_timer(&lp->timer);
750 }
751 #endif
752 
753 /* We have a good packet(s), get it/them out of the buffers. */
754 static void net_rx(struct net_device *dev)
755 {
756 	struct net_local *lp = netdev_priv(dev);
757 	long ioaddr = dev->base_addr;
758 	struct rx_header rx_head;
759 
760 	/* Process the received packet. */
761 	outb(EOC+MAR, ioaddr + PAR_DATA);
762 	read_block(ioaddr, 8, (unsigned char*)&rx_head, dev->if_port);
763 	if (net_debug > 5)
764 		printk(KERN_DEBUG " rx_count %04x %04x %04x %04x..", rx_head.pad,
765 			   rx_head.rx_count, rx_head.rx_status, rx_head.cur_addr);
766 	if ((rx_head.rx_status & 0x77) != 0x01) {
767 		dev->stats.rx_errors++;
768 		if (rx_head.rx_status & 0x0004) dev->stats.rx_frame_errors++;
769 		else if (rx_head.rx_status & 0x0002) dev->stats.rx_crc_errors++;
770 		if (net_debug > 3)
771 			printk(KERN_DEBUG "%s: Unknown ATP Rx error %04x.\n",
772 				   dev->name, rx_head.rx_status);
773 		if  (rx_head.rx_status & 0x0020) {
774 			dev->stats.rx_fifo_errors++;
775 			write_reg_high(ioaddr, CMR1, CMR1h_TxENABLE);
776 			write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);
777 		} else if (rx_head.rx_status & 0x0050)
778 			hardware_init(dev);
779 		return;
780 	} else {
781 		/* Malloc up new buffer. The "-4" omits the FCS (CRC). */
782 		int pkt_len = (rx_head.rx_count & 0x7ff) - 4;
783 		struct sk_buff *skb;
784 
785 		skb = netdev_alloc_skb(dev, pkt_len + 2);
786 		if (skb == NULL) {
787 			dev->stats.rx_dropped++;
788 			goto done;
789 		}
790 
791 		skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */
792 		read_block(ioaddr, pkt_len, skb_put(skb,pkt_len), dev->if_port);
793 		skb->protocol = eth_type_trans(skb, dev);
794 		netif_rx(skb);
795 		dev->stats.rx_packets++;
796 		dev->stats.rx_bytes += pkt_len;
797 	}
798  done:
799 	write_reg(ioaddr, CMR1, CMR1_NextPkt);
800 	lp->last_rx_time = jiffies;
801 }
802 
803 static void read_block(long ioaddr, int length, unsigned char *p, int data_mode)
804 {
805 	if (data_mode <= 3) { /* Mode 0 or 1 */
806 		outb(Ctrl_LNibRead, ioaddr + PAR_CONTROL);
807 		outb(length == 8  ?  RdAddr | HNib | MAR  :  RdAddr | MAR,
808 			 ioaddr + PAR_DATA);
809 		if (data_mode <= 1) { /* Mode 0 or 1 */
810 			do { *p++ = read_byte_mode0(ioaddr); } while (--length > 0);
811 		} else { /* Mode 2 or 3 */
812 			do { *p++ = read_byte_mode2(ioaddr); } while (--length > 0);
813 		}
814 	} else if (data_mode <= 5) {
815 		do { *p++ = read_byte_mode4(ioaddr); } while (--length > 0);
816 	} else {
817 		do { *p++ = read_byte_mode6(ioaddr); } while (--length > 0);
818 	}
819 
820 	outb(EOC+HNib+MAR, ioaddr + PAR_DATA);
821 	outb(Ctrl_SelData, ioaddr + PAR_CONTROL);
822 }
823 
824 /* The inverse routine to net_open(). */
825 static int
826 net_close(struct net_device *dev)
827 {
828 	struct net_local *lp = netdev_priv(dev);
829 	long ioaddr = dev->base_addr;
830 
831 	netif_stop_queue(dev);
832 
833 	del_timer_sync(&lp->timer);
834 
835 	/* Flush the Tx and disable Rx here. */
836 	lp->addr_mode = CMR2h_OFF;
837 	write_reg_high(ioaddr, CMR2, CMR2h_OFF);
838 
839 	/* Free the IRQ line. */
840 	outb(0x00, ioaddr + PAR_CONTROL);
841 	free_irq(dev->irq, dev);
842 
843 	/* Reset the ethernet hardware and activate the printer pass-through. */
844 	write_reg_high(ioaddr, CMR1, CMR1h_RESET | CMR1h_MUX);
845 	return 0;
846 }
847 
848 /*
849  *	Set or clear the multicast filter for this adapter.
850  */
851 
852 static void set_rx_mode(struct net_device *dev)
853 {
854 	struct net_local *lp = netdev_priv(dev);
855 	long ioaddr = dev->base_addr;
856 
857 	if (!netdev_mc_empty(dev) || (dev->flags & (IFF_ALLMULTI|IFF_PROMISC)))
858 		lp->addr_mode = CMR2h_PROMISC;
859 	else
860 		lp->addr_mode = CMR2h_Normal;
861 	write_reg_high(ioaddr, CMR2, lp->addr_mode);
862 }
863 
864 static int __init atp_init_module(void) {
865 	if (debug)					/* Emit version even if no cards detected. */
866 		printk(KERN_INFO "%s", version);
867 	return atp_init();
868 }
869 
870 static void __exit atp_cleanup_module(void) {
871 	struct net_device *next_dev;
872 
873 	while (root_atp_dev) {
874 		struct net_local *atp_local = netdev_priv(root_atp_dev);
875 		next_dev = atp_local->next_module;
876 		unregister_netdev(root_atp_dev);
877 		/* No need to release_region(), since we never snarf it. */
878 		free_netdev(root_atp_dev);
879 		root_atp_dev = next_dev;
880 	}
881 }
882 
883 module_init(atp_init_module);
884 module_exit(atp_cleanup_module);
885